Skylights are useful addition to almost any house. When selecting a skylight, you must be aware of the minimal functionality they offer. Skylights must allow for natural day lighting while reducing the heat. They must block the humid air from seeping in and similarly, warmth should not leak out of the house in winter. In areas prone to storms and hurricanes, skylights must withstand the forces of such natural terrors. When buying a skylight, there are few aspects that you should look into. U-factor: Skylights should preferably have U-factor below 0.75. This measures how efficient the material is in blocking the heat of the sun's rays. Higher the percentages, more the amounts of sunlight pass through the skylight. Visible Transmittance: Skylight must have higher values of Visible Transmittance. This simply means that more amount of light passes through them. Tinted coatings are preferred as they regulate the amount of light. Condensation Resistance: The higher condensation resistance rating means that the material is superior in preventing the formation of condensation. Generally, skylights must also be shaded properly to prevent excessive heat gain. Plastic skylights should be used minimally in hot climate areas as the heat and the sun's rays will soon discolor the plastic.